Numerous attempts have been made to wirelessly transmit energy to electronic devices, where a receiver can consume the transmission and convert it to electrical energy. However, most conventional techniques are unable to transmit energy at any meaningful distance. For example, magnetic resonance provides electric power to devices without requiring an electronic device to be wired to a power resonator. However, the electronic device is required to be proximately located to a coil of the power resonator (i.e., within a magnetic field). Other conventional solutions may not contemplate user mobility for users who are charging their mobile devices or such solutions do not allow devices to be outside of a narrow window of operability.
Wirelessly powering a remote electronic device requires a means for identifying the location of electronic devices within a transmission field of a power-transmitting device. Conventional systems typically attempt to proximately locate an electronic device, so there are no capabilities for identifying and mapping the spectrum of available devices to charge, for example, in a large coffee shop, household, office building, or other three-dimensional space in which electrical devices could potentially move around. Moreover, what is needed is a system for managing power wave production, both for directionality purposes and for power output modulation. Because many conventional systems do not contemplate a wide range of movement of the electronic devices they service, what is also needed is a means for dynamically and accurately tracking electronic devices that may be serviced by the power-transmitting devices.
Wireless power transmission may need to satisfy certain regulatory requirements. These devices transmitting wireless energy may be required to adhere to electromagnetic field (EMF) exposure protection standards for humans or other living beings. Maximum exposure limits are defined by US and European standards in terms of power density limits and electric field limits (as well as magnetic field limits). Some of these limits are established by the Federal Communications Commission (FCC) for Maximum Permissible Exposure (MPE), and some limits are established by European regulators for radiation exposure. Limits established by the FCC for MPE are codified at 47 CFR §1.1310. For electromagnetic field (EMF) frequencies in the microwave range, power density can be used to express an intensity of exposure. Power density is defined as power per unit area. For example, power density can be commonly expressed in terms of watts per square meter (W/m2), milliwatts per square centimeter (mW/cm2), or microwatts per square centimeter (μW/cm2).
Accordingly, it is desirable to appropriately administer the systems and methods for wireless power transmission to satisfy these regulatory requirements. What is needed is a means for wireless power transmission that incorporates various safety techniques to ensure that humans or other living beings within a transmission field are not exposed to EMF energy near or above regulatory limits or other nominal limits.